[PATCH 5.4 14/34] net: ping6: Fix memleak in ipv6_renew_options().

Greg Kroah-Hartman
2022-08-01T11:48:30Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

commit e27326009a3d247b831eda38878c777f6f4eb3d1 upstream.

When we close ping6 sockets, some resources are left unfreed because
pingv6_prot is missing sk->sk_prot->destroy(). As reported by
syzbot [0], just three syscalls leak 96 bytes and easily cause OOM.

struct ipv6_sr_hdr *hdr;
char data[24] = {0};
int fd;

hdr = (struct ipv6_sr_hdr *)data;
hdr->hdrlen = 2;
hdr->type = IPV6_SRCRT_TYPE_4;

fd = socket(AF_INET6, SOCK_DGRAM, NEXTHDR_ICMP);
setsockopt(fd, IPPROTO_IPV6, IPV6_RTHDR, data, 24);
close(fd);

To fix memory leaks, let's add a destroy function.

Note the socket() syscall checks if the GID is within the range of
net.ipv4.ping_group_range. The default value is [1, 0] so that no
GID meets the condition (1 <= GID <= 0). Thus, the local DoS does
not succeed until we change the default value. However, at least
Ubuntu/Fedora/RHEL loosen it.

$ cat /usr/lib/sysctl.d/50-default.conf
...
-net.ipv4.ping_group_range = 0 2147483647

Also, there could be another path reported with these options, and
some of them require CAP_NET_RAW.

setsockopt
IPV6_ADDRFORM (inet6_sk(sk)->pktoptions)
IPV6_RECVPATHMTU (inet6_sk(sk)->rxpmtu)
IPV6_HOPOPTS (inet6_sk(sk)->opt)
IPV6_RTHDRDSTOPTS (inet6_sk(sk)->opt)
IPV6_RTHDR (inet6_sk(sk)->opt)
IPV6_DSTOPTS (inet6_sk(sk)->opt)
IPV6_2292PKTOPTIONS (inet6_sk(sk)->opt)

getsockopt
IPV6_FLOWLABEL_MGR (inet6_sk(sk)->ipv6_fl_list)

For the record, I left a different splat with syzbot's one.

unreferenced object 0xffff888006270c60 (size 96):
comm "repro2", pid 231, jiffies 4294696626 (age 13.118s)
hex dump (first 32 bytes):
01 00 00 00 44 00 00 00 00 00 00 00 00 00 00 00 ....D...........
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000f6bc7ea9>] sock_kmalloc (net/core/sock.c:2564 net/core/sock.c:2554)
[<000000006d699550>] do_ipv6_setsockopt.constprop.0 (net/ipv6/ipv6_sockglue.c:715)
[<00000000c3c3b1f5>] ipv6_setsockopt (net/ipv6/ipv6_sockglue.c:1024)
[<000000007096a025>] __sys_setsockopt (net/socket.c:2254)
[<000000003a8ff47b>] __x64_sys_setsockopt (net/socket.c:2265 net/socket.c:2262 net/socket.c:2262)
[<000000007c409dcb>] do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80)
[<00000000e939c4a9>] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)

[0]: https://syzkaller.appspot.com/bug?extid=a8430774139ec3ab7176

Fixes: 6d0bfe226116 ("net: ipv6: Add IPv6 support to the ping socket.")
Reported-by: syzbot+a8430774139ec3ab7176@syzkaller.appspotmail.com
Reported-by: Ayushman Dutta <ayudutta@amazon.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220728012220.46918-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/ipv6/ping.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -22,6 +22,11 @@
#include <linux/proc_fs.h>
#include <net/ping.h>

+static void ping_v6_destroy(struct sock *sk)
+{
+ inet6_destroy_sock(sk);
+}
+
/* Compatibility glue so we can support IPv6 when it's compiled as a module */
static int dummy_ipv6_recv_error(struct sock *sk, struct msghdr *msg, int len,
int *addr_len)
@@ -165,6 +170,7 @@ struct proto pingv6_prot = {
.owner = THIS_MODULE,
.init = ping_init_sock,
.close = ping_close,
+ .destroy = ping_v6_destroy,
.connect = ip6_datagram_connect_v6_only,
.disconnect = __udp_disconnect,
.setsockopt = ipv6_setsockopt,